An active detection matrix, for example, a TFT-type plate that makes it possible to acquire an image representative of an incident radiation on a detector assembly, comprises a plurality of electro-optical cells arranged in rows and columns. In an ionizing radiation imaging application, a detector assembly can comprise such a detection matrix, then making it possible to acquire an image representative of the incident radiation on the detector assembly. Each cell of the arrangement can be controlled by a switching device, and can, for example, be controlled by the application of an electrical field applied via two electrodes bracketing the cell. The assembly consisting of the switching device, the electrodes and the cell is commonly designated “pixel”. The switching device can, for example, be formed by a switching transistor. For example, each row of the matrix can be connected to the gates of the switching transistors of a row of pixels. Thus, for each frame, the rows can be selected in sequence, one after the other in a direction of scanning of the rows of the matrix, during a row selection time corresponding to a fraction of the duration of the frame, allowing for the application of appropriate signals to the pixels of the row, for example voltages on the electrodes. Thus, the selection of a row corresponds to the application, during a corresponding row selection time, of a high-level signal controlling the passing state of the switching devices of the corresponding row of pixels. Outside of the row selection time, the switching devices are maintained in a blocked state via the application of an appropriate low-level signal. For example, when the switching devices are transistors, the signals to be applied then being voltages, it is usual practice to use VGon to designate the voltage corresponding to the high level and therefore to the passing state of the switching transistor, and VGoff to designate the voltage corresponding to the low level and the blocked state of the switching transistor.
In a manner known per se from the prior art, the rows can be controlled by control circuits comprising one or more shift registers in series, each of the shift registers comprising a plurality of cascaded stages, each stage being suitable for switching the high and low levels of the signal applied to the switching devices at the output on a corresponding row of the matrix, according to the sequencing of the selection of the rows, for example according to a vertical scanning. The control circuits can be implemented in integrated circuits, one and the same integrated circuit being able, for example, to comprise a plurality of control circuits for a plurality of rows of the matrix. The integrated circuits can, for example, be external to the matrix, and be connected thereto by wired means, for example by flexible ribbon cables. The integrated circuits can, for example, be directly mounted on the flexible ribbon cables, the latter connecting them not only to the matrix but also to a control and power supply circuit. Such systems however present the drawback of requiring complex production methods, and involve a large number of checks during fabrication. As well as a large number of repairs, due to the number of potential defects linked to all the steps of the production methods. An example of an existing system comprising integrated control circuits arranged on flexible ribbon cables is described in detail hereinbelow with reference to FIG. 1.
Another drawback with the known addressing systems is that the latter require the rows to be addressed one after the other, without it being permitted for a row not to be addressed; thus, the rows are addressed one after the other, and there is no pause between the addressing of two successive rows, the latter point potentially being particularly prejudicial when the matrix is used for detection purposes, for which it is necessary to allow an integration time for the charges originating from the pixels of the plate. Furthermore, these systems require all of the matrix to be addressed, according to a fixed addressing mechanism; now, it may in practice prove pointless, even prejudicial, to address all of the plate, for example in typical uses where the plate is used for detection purposes, notably in the context of x-ray imaging applications, in which the operator or the practitioner frequently takes care to view with an enhanced accuracy specific parts of the imaged scene, via so-called “zoom” operations.
The U.S. Pat. No. 5,536,932 describes a polysilicon multiplexer for two-dimensional image detection matrices.
The patent application published under the reference GB 2,317,742 describes an imaging device.
The patent application US 2002/172327 describes a radiological image detection system for a scanning x-ray generator.